miR-135b-5p regulates human mesenchymal stem cell osteogenic differentiation by facilitating the Hippo signaling...

A multifunctional titanium surface with osteogeneic, angiogeneic and antibacterial properties is needed to improve the osseointegration and long-term survival of dental implants. Particularly, the switch between the differentiation of mesenchymal stem cells (MSCs) into osteogenic and adipogenic lineages is regulated by numerous miRNAs. However, the association between miR-135b-5p and the Hippo signaling pathway during osteogenesis has not been elucidated. In the present study, we demonstrate that miR-135b-5p facilitates the in vitro osteogenesis of human mesenchymal stem cells (hMSCs).

hMSCs and Human Calvarial Osteoblasts (HCO) cells were cultured in vitro, followed by the transfection of the miR-135b-5p mimic or inhibitor using Lipofectamine 2000. The target of miR-135b-5p was determined by bioinformatics analysis and luciferase assay. Cell viability was tested using the MTT assay. The osteogenesis level was evaluated by alizarin red staining. miRNA and mRNA expression levels were detected by real-time PCR. The protein levels were assessed by western blotting.

miR-135b-5p was shown to be highly expressed in osteoblasts compared with that in hMSCs. The overexpression of miR-135b-5p promotes hMSC proliferation and osteogenesis, whereas its knockdown causes the inhibition of these processes. Furthermore, aberrant expression of miR-135b-5p promotes both osteogenic and proliferation factors. We next showed that the Hippo signaling pathway was activated by miR-135b-5p transfection. Next, we found that large tumor suppressor 1 (LATS1) and MOB kinase activator 1B (MOB1B), key negative regulators of the HIPPO signaling pathway, are direct targets of miR-135b-5p. In addition, the knockdown of LATS1 or MOB1B led to an increase in TEAD activity.

miR-135b-5p regulates osteogenesis by controlling LATS1 and MOB1B expression and subsequently activating the HIPPO signaling pathway.